Hello group,
Some "on air"-tests performed saturday evening showed no big difference in the
performance of PSK08 with amplitude shaping and "slow phase" variation. Thanks to DF6NM's
grabber (with the zoomed range switched to 136500 Hz temporarily) I could not observe a broader
signal when switching between the two PSK shaping methods.
Also interesting: Shortly after starting, DL3ZID called me (also in PSK08), and Eberhard was
perfect copy (as long as no local QRM carriers wiped him out) with 5 mW ERP from over 100 km's
distance, though the PSK signal was almost invisible on the QRSS3-spectrogram. So the good old
waterfall display may be not very helpful to detect the presence of such a signal - unless a kind
of "weak pilot tone" if added to the signal, which would allow to adjust the RX frequency
manually (by moving the L.O. frequency with a mouseclick into the waterfall, etc). During the QSO
with DL3ZID, the AFC'ed RX frequency was pulled away several times by "wandering
carriers" so I finally turned it off (no problem, since DL3ZID's TX frequency was stable
enough).
Locking the "soft" L.O. to a selectable Loran line may be another option to
circumvent these problems.. but that's another story.
Regards,
Wolf DL4YHF.
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